This invention relates to motorcycle trailers, and more particularly to a motorcycle trailer having a variable ground clearance torsion bar suspension system.
A vehicular height adjusting mechanism implemented by means of a torsion bar suspension system is shown in U.S. Pat. No. 4,243,247 granted to Kataoka. Such a system commonly includes a torsion bar offset from the axis of the road wheel but parallel to such axis. A suspension axis perpendicular to the wheel axis connects the wheel spindle to a torque tube rotatably connected to the body of a vehicle. The torque tube has a torsion bar disposed within it. The torsion bar has one end connected to the body of the vehicle by means of a bracket.
Motorcycle trailers are used to bring "dirt bikes" to remote locations over rough terrain. In order to avoid overturning the trailer and the consequent ruin of the motor bike, it is desirable that the trailer have as low a center of gravity as possible. The requirement of a low center of gravity for a trailer used on rough terrain places constraints on the design of a trailer undercarriage. The undercarriage should be free of projections that would strike rocks or other elements of rough terrain.
In addition to the increased stability afforded by a low center of balance, this profile is also more appropriate for the cargo handling environment in which the trailer is typically found. A large motorcycle can be loaded or unloaded with less effort as the trailer ground clearance decreases. For recreational uses, loading convenience is particularly important.
While the height adjusting mechanism shown in U.S. Pat. No. 4,243,247 significantly decreases the under carriage space consumed by the torsion bar suspension apparatus, there still remain several undesirable under carriage projections. The transverse torque tube with supporting brackets must be accommodated under the trailer. The presence of these elements beneath the trailer create clearance problems and also expose such elements to the likelihood of damage during use.
There is a need for a torsion bar suspension system wherein the torsion bar is aligned with the direction of travel and thereby presenting as small an area to oncoming hazards as possible. It is also desirable that the torsion bar be disposed at the side of the trailer rather than beneath so that all hazards are avoided. In short, it is desirable that the under carriage of the trailer be completely smooth.
No prior art device meets these criteria. For example, U.S. Pat. No. 2,806,710 granted to Mascaro discloses a trailer having vertically adjustable wheels. The undercarriage of the Mascaro trailer has numerous tranverse members exposed to the hazards of rocky terrain. In addition, the Mascaro apparatus is excessively complicated and bulky.